creating ssh-wise identical machines

Andreas Schuldei Wed, 14 Dec 2005 08:14:11 -0800

I work on debian with openssh 1:3.8.1p1-8.sarge.4

I am building an UserModeLinux machine for automated test
purposes and copy the dsa and rsa files from /etc/ssh/ onto the
uml (and set the permissions correctly).  I also put my personal
ssh public key into the uml's root dir during install.  Now I
get this warning when I connect to the uml from my host machine:


WARNING: DSA key found for host 10.0.2.2
in /home/andreas/.ssh/known_hosts:38
DSA key fingerprint e9:d7:8b:fa:79:70:8c:cf:05:c2:09:70:49:0c:3a:cd.
The authenticity of host '10.0.2.2 (10.0.2.2)' can't be established
but keys of different type are already known for this host.
RSA key fingerprint is 95:10:a8:18:68:74:75:3a:db:33:0c:cd:18:e0:87:bf.

I dont really understand what the problem might be. All four keys
are there and fine after each uml install and identical with the
originals (checked the sha1sum of them).  do i need more files to
make the uml machines appear identical after reinstall?


======================
for entertainment, this is how i handle the copying of the files:

ome reason the user's homedir is a read only filesystem during 
# the rootstrap run.

if [ ! -d $data ]; then
    mkdir $data
fi

if [ -f $data/ssh_host_rsa_key -a -f  $data/ssh_host_rsa_key.pub ]; then
    cat $data/ssh_host_rsa_key     | \
        chroot $TARGET sh -c "cat > /etc/ssh/ssh_host_rsa_key"
    cat $data/ssh_host_rsa_key.pub | \
        chroot $TARGET sh -c "cat > /etc/ssh/ssh_host_rsa_key.pub"
    chroot $TARGET chmod 600 /etc/ssh/ssh_host_rsa_key
    chroot $TARGET chmod 644 /etc/ssh/ssh_host_rsa_key.pub
else
    chroot $TARGET cat /etc/ssh/ssh_host_rsa_key \
        > $data/ssh_host_rsa_key
    chroot $TARGET cat /etc/ssh/ssh_host_rsa_key.pub \
        > $data/ssh_host_rsa_key.pub
fi

if [ -f $data/ssh_host_dsa_key -a -f  $data/ssh_host_dsa_key.pub ]; then
    cat $data/ssh_host_dsa_key     | \
        chroot $TARGET sh -c "cat > /etc/ssh/ssh_host_dsa_key"
    cat $data/ssh_host_dsa_key.pub | \
        chroot $TARGET sh -c "cat > /etc/ssh/ssh_host_dsa_key.pub"
    chroot $TARGET chmod 600 /etc/ssh/ssh_host_dsa_key
    chroot $TARGET chmod 644 /etc/ssh/ssh_host_dsa_key.pub
else
    chroot $TARGET cat /etc/ssh/ssh_host_dsa_key     > $data/ssh_host_dsa_key
    chroot $TARGET cat /etc/ssh/ssh_host_dsa_key.pub > 
$data/ssh_host_dsa_key.pub
fi


if [ -f $home/.ssh/id_rsa.pub ]; then
    cat $home/.ssh/id_rsa.pub | chroot $TARGET sh -c "mkdir /root/.ssh; chmod 
700 /root/.ssh; cat >> /root/.ssh/authorized_keys"
fi

if  [ -f $home/.ssh/id_dsa.pub ]; then
    cat $home/.ssh/id_dsa.pub | chroot $TARGET sh -c "mkdir /root/.ssh; chmod 
700 /root/.ssh; cat >> /root/.ssh/authorized_keys"
fi

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creating ssh-wise identical machines

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